Anyone having trouble playing YouTube videos? Recently for me they are very slow to load and jerky...etc. Even when you let the video fully load and then play it, it's jerky and freezes for a moment from time to time.

If THAT doesn't work, do all of that, but after rebooting in the middle, delete their C:\Program Files\ folders and use the "Registry scan/fix option" in CCleaner (search Google, it's free) to clean out orphaned entries from the registry, reboot and reinstall.

I'm also thinking you might have installed some 3rd party app or got spyware/malware/trojan/rootkit/whatever. Maybe try Spybot (I love the Immunize feature in there as well) and Malwarebytes. all frweeeeeeeeee